Intel IXP43X manual on page on page, Timing Relationships, Signal Package Lengths Sheet 1 of

Intel® IXP43X Product Line of Network Processors—Hardware Design Guidelines

—Table 31 on page 79

Data Group to Strobe Summary:

•The more restrictive data group to strobe timing occurs for read operations

—Table 32 on page 80

—Table 33 on page 80

•The maximum allowable difference from any data group signal to the strobe is ±0.25 ns.

—Figure 30 on page 77

—Table 32 on page 80

Strobe to Clock Summary:

•The maximum allowable difference from any data strobe signal to the clock is - 0.475 ns to +0.875 ns

—Figure 32 on page 83

—Table 34 on page 83

These are absolute maximum ratings for length mismatch based in ideal printed board conditions (exact signal propagation delays, ideal signal integrity with no reflections or settling, zero rise/fall times, and so on.). To compensate for these non-ideal conditions, more restrictive length matching conditions should be used based on signal integrity analysis and simulation to provide a buffer zone and avoid possible variations in silicon or printed circuit board manufacture.

Table 32.	Timing Relationships
	Signal Group	Absolute Minimum Length	Absolute Maximum Length
	Control to Clock	Clock – 600 ps	Clock + 600 ps
	Command to Clock	Clock – 600 ps	Clock + 600 ps
	Data to Strobe	Strobe – 250 ps	Strobe + 250 ps
	Strobe to Clock	Clock – 475 ps	Clock + 875 ps

In addition to any trace length differentials which must be considered between signal groups, differences in the package length between signals should be considered when determining the total propagation delay of the signals. When using the IXP435 reference platform IBIS model for signal analysis, package characteristics are included in the simulation results.

Table 33.	Signal Package Lengths (Sheet 1 of 3)
	Group	Signal Name	Length (mil)	Signal Name	Length (mil)
		D_CK_N0 /	558.19	D_CK0 / DDR_CK0	507.46
		DDR_CK_N0
	Clock	D_CK_N1 /	385.12	D_CK1 / DDR_CK1	385.12
		DDR_CK_N1
		D_CK_N2 /	504.20	D_CK2 / DDR_CK2	548.01
		DDR_CK_N2

Intel® IXP43X Product Line of Network Processors
HDG	April 2007
80	Document Number: 316844; Revision: 001US